Why look for a new theory of gravity if the big bang cosmology is correct?

Occasionally we read in the popular press, especially online, that someone has come up with a new theory of gravity. Why is that even necessary if the current theory describing the evolution of the universe is so correct?

The standard ΛCDM big bang cosmology is derived from an application of certain non-biblical boundary conditions to the physics of Einstein’s general relativity theory. But when that was applied to the universe as a whole, two problems developed for the secular model. One is the need to add in dark energy (or the cosmological constant, Λ (Lambda), to Einstein’s field equations) and the other is the need for a significant amount of invisible cold dark matter (CDM).

On the scale of galaxies and even clusters of galaxies Newtonian physics is used as it is the low gravity limit of general relativity. But without the addition of dark matter the resulting theory, using the known density of visible matter in galaxies (see Fig. 1) and clusters, does not match observations. But for more than 40 years now dark matter has been sought in various lab experiments with consistently negative results. This has developed into what is called the dark matter crisis.1

Figure 1: Typical rotation curve of a spiral galaxy: Speeds (V) in km/s units as a function of distance from the centre of the galaxy (R) in 1000 light-year (ly) units. The upper curve shows the speeds of the stars in disk region determined from their visible light and the gasses beyond that determined from radio frequency emissions. The lower curve shows what standard Newtonian physics predicts should be observed. The discrepancy is made up by positing the existence of invisible dark matter. Credit: Wikipedia

Occasionally a claim is made that a theorist has some inkling of what dark matter particles might be but the crisis remains.2 Dark matter particles have been sought without success in the Galaxy using very sensitive detectors deep in underground mines,3 or with the Large Hadron Collider (LHC) over 10 years of experiments looking for the lowest mass stable particle in a theorised class of as-yet-undiscovered supersymmetric particles.4

The observational data from thousands of galaxies together with the negative outcome of all the experiments searching for Dark Matter particles indicate that either something is wrong with the physics we use or that the expected dark matter is much more elusive than supposed, or, indeed, does not, in fact, exist—which gets us back to something being wrong with the physics.

This same type of problem also applies to the concept of dark energy, which was introduced into the big bang to explain observations that were interpreted to indicate that the expansion rate of the universe was actually increasing over cosmic time, that is, the expansion is accelerating. The question of the identity5 of this ‘anti-gravity’ dark energy has also gone unanswered. It has been suggested that the answer may lie with a particle called a chameleon.6 Only in empty space does the hypothesized chameleon particle take on the characteristics which provide a new anti-gravity force in the universe, hence dark energy. But when you look for it near Earth it takes on a new identity and hides itself so you cannot find it.

To explain dark matter, new physics has been proposed. These include Milgrom’s MOdified Newtonian Dynamics (or MOND)7 and Bekenstein’s Tensor-Vector-Scalar gravity (or TeVeS) a relativistic theory of modified gravity.8 Although not initially intended to address the Dark Matter crisis, I found that Carmeli’s Cosmological General Relativity (CGR) explained the existing observations with no need for either dark matter or dark energy.

Now some have suggested that, when the large-scale observational data10 for the universe as a whole are all taken into account, dark energy does not need to be included, as the observations applied to the standard cosmology are consistent with no acceleration. The author of one such study said:10

“… it is quite possible that we are being misled and that the apparent manifestation of dark energy is a consequence of analysing the data in an oversimplified theoretical model…”

Moreover, it was noted even earlier that

[a]n alternative possibility … can explain the observations as a fluke of cosmological geometry. It avoids invoking dark energy as an ad hoc cause but at the price of throwing out the Copernican principle: roughly speaking, it puts the Earth, or at least our galaxy, back at the centre of the observable universe.11

The Copernican principle is, of course, an arbitrary condition imposed on the interpretation of cosmological observations in order to avoid the possibility that the Earth has a unique location in the universe, something one might conclude from reading Genesis.

Now a new idea has entered this arena.12

In 2010, Erik Verlinde surprised the world with a completely new theory of gravity. According to Verlinde, gravity is not a fundamental force of nature, but an emergent phenomenon. In the same way that temperature arises from the movement of microscopic particles, gravity emerges from the changes of fundamental bits of information, stored in the very structure of spacetime.13

This new theory describes gravity as “emergent”, meaning that it is not fundamental but ‘emerges’ from the universe as it cooled from the initial hot big bang fireball. Verlinde said “At large scales, it seems, gravity just doesn’t behave the way Einstein’s theory predicts.”13 His approach is new physics. That may be a much more reasonable approach than looking for all the dark sector entities that are now invoked,14 largely to fill in where the standard physics has failed.

My focus here is not to attempt to decide which theory of gravity is correct. I want to ask a different question. If what we are told is true—i.e. that big bang cosmology is essentially complete and the big bang origin of the universe correct—why do these physicists even look for new physics? Is it not because as time goes by the research problem of the non-detection of dark matter, dark energy, dark radiation15 (a sterile neutrino), dark photons,16 chameleons6 and many more dark entities17 starts to indicate that the whole paradigm itself is in doubt? Surely the very concept of a universe that created itself from nothing (without a Creator God) must be thrown into doubt. And does this search for a new physics not validate other proposals of new physics that attempt to explain the observed phenomenon in a way consistent with the biblical creation account in the Bible, such as those proposed by Dr. Russell Humphreys18,19 or myself?20,21

The Universe needs a First Cause, a Creator, and that just will not do for the unbelieving world.

I conclude that the secular pursuit of new physics to solve big bang cosmology problems, like their ‘god of the gaps’22dark matter crisis, is really an attempt to stave off acceptance of what the Creator told us thousands of years ago,

Milgrom modified gravity to make the strength of its force inversely proportional to distance in weak gravitational fields. This contrary to standard Newtonian gravity which is inversely proportional to distance squared. Milgrom’s theory can account for the observed orbital speeds of stars and gasses as shown in Fig. 1 without the need for dark matter. But Milgrom has no underlying fundamental reason why such a modification should be made except by tuning it to observations.

Bekenstein introduced a relativistic generalisation (hence more fundamental) of Milgrom’s MOND to produce a mechanism why gravity is modified in the limit of weak accelerations. In the weak-field approximation of the spherically symmetric, static solution, TeVeS reproduces the MOND acceleration formula.

From type Ia supernovae, which led to the Nobel prize in physics in 2011, for detection of an accelerating universe.

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6 thoughts on “Why look for a new theory of gravity if the big bang cosmology is correct?”

Dear John and all, thank you for your updates and counter-weights to the endless stream of ’causeless’ science. I struggle to get the understanding of your articles, not through any lack on your end, simply my lack of in depth knowledge on the subject. But this time the point hit home. Great thinking, please keep pursuing your goal! My prayers for your even greater understanding are sent along with this simple ‘THANK-YOU’. Yours, Barry Saunders